Wall thermostat housing unit



Aug. 31, 1965 A. E. BAAK WALL THERMOSTAT HOUSING UNIT 2 Sheets-Sheet l Filed Deo. 14, 1960 ALBERT 1. HAMM, 104 95 M0 78 142 INVENTOR BY l-/fs rranwsgs.

,HRR/Q K 155W, Rassen, Ke/a N.

Aug. 3l, 1965 A. E. BAAK WALL THERMOSTAT HOUSING UNIT 2 Sheets-Sheet 2 Filed DeC. 14, 1960 m w A IN VEN TOR.

.HQR/s, MECH, RusssLL. en/

varms of the mounting plate.

United States Patent O 3,204,073 WALL THERMGSTAT HOUSING UNIT Albert E. Baak, 640 Ocampo Drive, Paciiic Palisades, Calif. Filed Dec. 14, 1960, Ser. No. 75,784 3 Claims. (Cl. 20G- 168) This invention relates to thermostats and provides several improvements in thermostat construction.

Wall thermostats `are conventionally installed in a single piece. It has been frequently experienced, especially in large housing projects, that thermostats are purloined from the wall of a new house before the house is occupied. To forestall the loss of thermostats it is now general practice for an electrician to return to the house shortly before occupancy to complete the necessary electrical connnections and install the thermostats.

The improved wall thermostat of the invention has as one of its components a mounting plate adapted for independent connection to the wall, the mounting plate being provided with a set of terminal connections for grasping Wire leads and terminal arms connected to the terminal connections. Two, three or more terminal connections with a like number of terminal arms will be provided, the number depending on the requirements of the particular thermostat design. With the mounting plate properly positioned on the wall, the terminal arms appear on the exposed face of the plate. The second major component of the improved wall thermostat is a thermostat housing adapted to be removably held to the mounting plate. A second set of terminal arms is supported within the housing which arms are oriented for removably interlocking with corresponding terminal arms of the mounting plate. The thermostat housing is preferably removably held to the mounting plate through the interlocking of the terminal arms of the housing member and the mounting plate.

In a preferred embodiment of the wall thermostat of the invention the mounting plate takes the form of a circular disc and is made of an insulating7 material. The circular mounting plate is adapted for independent connection to the Wall. The mounting plate is provided with a set of terminal connections for grasping wire leads and terminal arms connected to the terminal connections, with the terminal arms being exposed when the mounting plate is iXed to the wall. The removable thermostat housing has adjacent the mounting plate a hollow bottom portion defined by a wall possessing an inner diameter slightly larger than the diameter of the circular mounting plate. This wall at its inner side carries an annular ledge, which ledge has an inside diameter less than the diameter of the circular mounting plate. The ledge is spaced from the bottom of the housing a distance approximating the thickness of the circular mounting plate. A set of terminal arms corresponding in number to the terminal arms of the mounting plate is supported within the housing with their ends oriented to interlock with corresponding Preferably, the circular mounting plate has two openings which may be placed at the periphery of the circular plate or interiorly, over which opening the terminal arms of the mounting plate are positioned. In a thermostat having more than two Awire leads, additional openings will be provided in the mounting plate with an additional terminal arm being positioned over each of the additional openings. Each additional wire lead to the thermostat will, of course, require a separate terminal connection. The outer ends of the terminal arms supported within the thermostat housing are respectively positioned within the openings of the circular mounted plate and in this position interlock with the terminal arms carried by the mounting plate.

Other advantages and objects of the invention will become apparent to those skilled in the art from the follow- 3,204,073 Patented Aug. 31, 1965 lCC ing description of a preferred form of the invention, it being understood that other modiiications and changes may be made.

In the drawings:

FIG. 1 is an isometric view of a preferred embodiment of the thermostat of the invention with a shroud enclosing the thermostat housing proper;

FIG. 2 is a cross-sectional View taken along line 2-2 of FIG. 1;

FIG. 3 is a rear elevational view taken along line 3--3 of FIG. 2 of the thermostat housing illustrating the mechanism housed therein including the bimetal blade supported by a combination heater and bimetal blade bracket;

FIG. 4 is an exploded isometric view of an assemblage at the outer end of the bimetal blade, with the bimetal blade being shown in section;

FIG. 5 is an elevational view taken along l-ine 5-5 'of FIG. 2 illustrating the mounting plate aixed to the wall with the shroud and thermostat housing being indicated in phantom lines in an initial position taken by those two members during their coupling to th-e mounting plate with the outer ends `of -two terminal arms carried by the housing being oriented adjacent corresponding terminal arms of the ymount-ing plate;

FIG. 6 generally resembles FIG. 5 with the respective terminal arms of the plate and housing being interlocked and with the shroud and housing assuming their fully mounted positions;

FIG. 7 is a sectional view taken along line 7-7 Iof FIG. 5 illustrating the terminal arms of the mounting plate and housing respectively in an adjacent and unlocked position;

FIG. 8 is a sectional View taken along line 8 8 of FIG. 6 illustrating the terminal arms of FIG. 7 in their locked position, which occurs with the twisting of the housing and shroud clockwise from the position of FIG. 5 to that of FIG. 6;

FIG. 9 is an isometric view of t-he combination heater and bimetal blade bracket seen in elevation in FIG. 3

with a portion of the bimetal blade being attached thereto;

FIG. 1G is a cross-sectional View taken along line '1li- 10 of FIG. 3 illustrating the manner of support for the combination heater and bimetal blade bracket of FIG. 9; and

FIG. ll is `a sectional View through the bimetal blade illustrating its structure at its unsupported end and manner of engaging the stationary contact to complete a circuit.

There is illustrated in FIGS. 1-3 inclusive a wall thermostat 10 made up of three principal component parts including a mounting plate 12 aiixed to a wall 14, a hollow thermostat housing 16 which contains the mechanism of the thermostat, and a removable shroud 18 which in the embodiment illustrated has a generally rectangular cross section.

The thermostat housing 16 which is generally circular 4in cross section has a front recess 20 separated by a circular wall 22 from a rear recess 24. The wall 22 serves as a bulkhead separating the mechanism positioned in the rear recess 24 from an adjustable circular dial 28 (see FIG. 2) made of a transparent material such as Lucite which is rotatably mounted in the front recess 20 of the thermostat housing 16. The front side of the bulkhead wall 22 has atiixed to it a scale plate 30 which has painted on it an upper and a lower temperature scale 32 and 34. In an alternative embodiment the scales may be painted directly on the front of the bulkhead wall 22 obviating need for the scale plate 30. The adjustable dial 28 is held within the front recess 20 by a shaft 36 which passes through a centrally located hole of the bulkhead wall 22 and carries at its rear end a cam a anger/e member 38. The cam member 33 is ixed to the shaft 36, being held thereto by a screw 39 which threadedly engages a hole in the end of the shaft 36. Thus, turning of the adjustable dial 28 moves the cam 38. The adjustable dial 28 also has xed to it an upper pointer 40 which may be moved with the turning of the dial 28 along the temperature scale 32. As will hereinafter be seen, the positioning of the pointer 40 at a temperature along the scale 32 results in the thermostat being activated (either opening or closing) when the actual room temperature reaches that of the setting.

The shaft 36 has encircling it but not xed to it a bimetal type coil spring 42 which has its outer, free end bent to form a pointer 44. This bimetal coil spring 42, which operates independently of the shaft 36, records the true room temperature which is reported on the lower scale 34.

As best seen in FIG. 2, the outer wall of the rear recess 24 is provided with a series of cutout portions or vents 46 which permits the flow of room air to the mechanism housed in the rear recess 24. In order for the room air to reach the thermostat mechanism, it is imperative that the shroud 18 stop short of the wall 14; otherwise the vents 46 would be blocked.

The mounting plate 12 (see FIGS. 5 and 6) has several holes 48 through which screws 49 may extend to hold the mounting plate to the wall 14. The circular mounting plate 12 which is in actuality a thin disc formed of an insulating material such as a phenolic plastic has on its perimeter two notched areas or openings 50. The mounting plate is also provided with an interiorly located hole 52 through which wiring 54 may pass. The mounting plate 12 on its inner face carries two terminal clip members 56 and 58 of considerably different configuration, but having essentially the same components. Each terminal clip member is provided with a terminal connection 60 to which a lead of the wiring 54 is connected. The particular terminal connections 60 employed take the form of a screw. Each terminal clip member 56 and 58 has at its outer end a terminal arm 62 positioned over one of the notched areas 50. The terminal arms 62 are somewhat flexible. The mounting plate 12 has a third peripheral notched area 64 which, as best seen in FIG. 10, is designed to receive a screw 66 that penetrates the wall of the thermostat housing 16, thereby serving to lock the housing 16 with respect to the mounting plate 12 to forestall rotational movement of the housing relative to the plate 12.

The mechanism housed in the rear recess 24 of the thermostat housing 16 includes the aforementioned cam member 38, a combination heater and bimetal blade bracket 68 which supports a bimetal blade 70, a magnet and contact screw support bracket 72, a contact screw 74 and a U-shaped Alnico permanent magnet 76. The contact screw 74 and magnet 76 are carried by the aforementioned bracket 72. The magnet and contact screw bracket 72 are held by several rivets 7 8 to a step-up portion of the bulkhead wall 22. The aforementioned cam member 38 and the combination heater and bimetal blade bracket 68 is held to a step-down portion 82 of the bulkhead Wall 22.

The combination heater and bimetal blade bracket 68 (see FIGS. 3, 9 and 10) is supported by a single pivot member 84 to the bulkhead wall 22. To achieve a satisfactory one-point support, the bracket 68 is formed with a rearwardly extending arm member 86 which at its rearward end is bent inwardly to provide a pivot member support portion 88, which portion 88 has an elongated notch 90 between upper and lower bearing ngers 92 and 94. As best seen in FIG. l0, the upper bearing linger 92 is offset with respect to the lower bearing finger 94; that is, they do not fall in the same vertical plane. The pivot member 84 adjacent its free end is provided with a groove 96 in which the upper bearing iinger 92 rests with the lower bearing nger 94 engag- 5. ing the outermost end portion of the pivot member 84 beyond the groove 96.

The combination heater and bimetal blade bracket 68 is an irregularly shaped pi-ece having at its lower side a protractor-shaped, integrally formed portion 98 having an arc-like segment 160 over which a heater Wiper 102 may be moved. The pointer of the heater Wiper 102 engages the surface of the arc segment 100. A bobbin frame 1114 formed of an insulating material such as linen melamine has wrapped about ita heater coil 105 formed of enamel insulated wire 106. One end of the heater coil 105 is fastened to a lead 108. The exposed surface of the wire coil 105 has the enamel insulation removed, thus providing a circuit via the wire of the heater coil 105 and the wiper 102 to the arc segment 100. As best seen in FIG. 9, the nonpointer end of the heater wiper 162 has a turned-in ear 110 that engages the upper surface of the wire coil 105. Movement of the heater wiper 1112 lengthens or shortens the path of the current through the resistance coil. The described heater, while not necessarily employed in all thermostats, serves to reduce the lag in actuation of the thermostat that might otherwise occur in the absence of a heater.

The upper portion of the combination bracket 68 has two spaced arms 112 and 114, each having at its outer end an internally threaded hole in alignment with the corresponding hole of the other arm. A cam following screw 116 threadedly engages the holes of the two arms 112 and 114. The lower end of the cam following screw 116 contacts a cam surface 118 at the cam member 38. Movement of the cam member 38 by turning of the adjustable dial 28 raises and lowers the cam following screw 116. The bimetal, temperature-sensitive blade 70 at its fixed end is attached to the rearwardly extending arm member 86. An upwardly extending spring member 119 afiixed to the aforementioned rearwardly extending arm member 86 at its upper end engages the inner wall of the rear recess 24.

The outer end of the bimetal blade 70 (see FIG. 4) has a notched area 120 and a downwardly-set end portion 122. This outer end of the bimetal blade 70 carries an assembly made up of a contact blade spring 124 and an L-shaped armature 126. The contact blade spring 124 which is held between the overlying bimetal blade 70 and the armature 126 is formed of conductive, liexible material and has an elongated opening 128 separating two arms 130 and 132. The free end of the arm 132 rests on the armature 126 but may be moved upwardly since no portion of the bimetal blade 70 overlies it. The unattached inner end of the contact blade spring 124 may also flexed to some degree since the overlying bimetal blade 70 does not normally engage the contact blade spring because of the aforementioned step-down portion.

Each of the arms 130 and 132 carries on its underside a palladium contact 134 which takes the form of a short peg. Both of the palladium contacts 134 upon lowering of the bimetal blade 70 contact the head of the contact screw 74. It will be appreciated that this manner of holding the contact blade spring 124 to the bimetal blade 70 permits independent flexing of the two arms 130 and 132, which is particularly desirable if one of the contact members should become contaminated with dirt.

The bracket 72, in addition -to supporting the aforementioned contact screw 74 between two spaced arms 136 and 138, carries a magnet 76. The magnet 76 in cooperation with the armature member 126 provides positive contact of the bimetal blade 70 with the contact screw 74.

The wall of the thermostat housing 16 at its rear side immediately a-dacent the mounting plate 12 has .an inside diameter slightly larger than the diameter of the circular mounting plate 12. The inner Wall of the thermostat housing 16 close to the rear side of the housing is provided with an inwardly-extending, discontinuous annular ledge 140. The ledge 1411 is spaced from the rear of the housing a distance approximately the thickness of the circular mounting plate 12. With this arrangement, the circular mounting plate 12 is contained wholly within the thermostat housing 16 when the two components are in their assembled form (see FIG. 2).

The magnet and contact screw bracket 72 adjacent its outside edge supports an integrally formed, rearwardly extending terminal arm 142. The rear recess 24 also houses a second terminal arm 144 which is held by two rivets 146 to the step-down portion of the bulkhead wall 22. The aforementioned wire lead 108 which is fastened to one end of the heater coil 105 is at its other end soldered to the terminal arm 144.

FIGS. 5 and 6 illustrate the manner in which the thermostat housing 16 is positioned on the mounting plate 12. The rear, open end of the housing 16 is placed over the circular mounting plate 12, with the circular mounting plate coming to rest on the annular ledge 140 Within the thermostat housing proper. In this position the terminal arms of the mounting plate 12 and thermostat housing 16 are adjacent but out of contact with each other as illustrated in FIGS. 5 and 7. The housing 16 and the shroud 18 mounted thereon are then turned clockwise to assume the position illustrated in FIG. 6. In this latter position the corresponding terminal arms of the mounting plate 12 and thermostat housing 16 interlock. The screw 66 is positioned as illustrated in FIG. 6 to forestall rotational movement of the thermostat housing 16 relative to the mounting plate 12. To remove the thermostat housing 16 the screw 66 is withdrawn from the peripheral notch 64 of the mounting plate 12 and the thermostat housing 16 is turned counterclockwise to disengage the respective terminal arms. Once the terminal arms of the mounting plate 12 and housing 16 have been disengaged, the housing may be removed from the plate 12.

Although an exemplary embodiment of the invention has been disclosed herein for purposes of illustration, it will be understood that various changes, modifications, and substitutions may be incorporated in such embodiment without departing from the spirit of the invention as defined by the claims which follow.

I claim:

1. In an improved Wall thermostat, the improvement comprising: a circular mounting plate having a thin disc configuration and formed of insulating material and designed for independent connection to the wall, said plate being provided with a set of terminal lconnections and terminal arms connected to said terminal connections, said mounting plate upon connection to the wall having said terminal arms exposed; a thermostat housing removably held tothe mounting plate and having adjacent said mounting plate a hollow rear portion with a wall possessing an inner diameter slightly larger than the diameter of said circular mounting plate placed about said mounting plate; and a second set of terminal arms supported within said housing with their outer ends removably interlocked with corresponding arms of the mounting plate, said corresponding terminal arms of the mounting plate and housing having complementary structures that engage with relative rotation of the housing and mounting plate.

2. In an improved wall thermostat, the improvement comprising: a circular mounting plate having a thin disc conliguration and formed of insulating material designed for independent connection to a wall, said mounting plate having at least two openings and a hole for wiring; terminal clips aflixed to one face of the mounting plate with each of said clips having a terminal arm positioned over one of the openings of the mounting plate and means for grasping a wire lead, said mounting plate upon connection to the wall having said one face exposed; a thermostat housing yremovably held tothe mounting plate and having adjacent said mounting plate a hollow rear portion having a wall possessing an inner diameter slightly larger than said circular mounting plate, said wall at its inner side being provided with an annular ledge having an inside diameter less than the diameter of said circular mounting plate, said ledge being spaced from the rear of said housing a distance approximately the thickness of said circular mounting plate; and a -second set of terminal arms supported within said housing with their outer ends positioned within the openings of the circular` mounting plate and removably interlocked with corresponding terminal arms carried by the mounting plate, said corresponding terminal arms of the mounting plate and housing having complementary structures that engage with relative rotation of the housing and mounting plate.

3. In Ian improved Wall thermostat, the improvement comprising: a circular mounting plate having a thin disc conguration and formed of insulating material and designed for independent connection to the wall, said plate being provided with a set of terminal connections for grasping wire leads and terminal arms connectedl to said terminal connections, said mounting Aplate upon connection to the wall having said terminal arms exposed; a thermostat housing removably held to the mounting plate and having adjacent said mounting plate a hollow rear portion having a wall possessing an inner diameter slightly larger than the diameter of said circular mounting plate, said wall at its inner side being provided with an annular ledge having an inside diameter less than the diameter of said circular mounting plate, said ledge being spaced from the rear of said housing a distance approximately the thickness of said circular mounting plate; and a second set of terminal arms supported Within said housing with their outer ends removably interlocked with corresponding arms of the mounting plate, said corresponding terminal arms of the mounting plate and housing having complementary structures that engage with relative rotation of the housing and mounting plate.

References Cited by the Examiner UNITED STATES PATENTS 923,887 6/09 Platt 339--189 1,657,486 1/28 Scott 200-168 2,127,473 8/38 Sacco 339--189 2,267,484 12/ 41 Van- Houten 200-138 X 2,415,473 2/47 Dougherty 200-138 2,581,308 l/52 Smith 200-50 2,857,486 10/ 58 Hubbell et all. 200--50 2,864,918 l2/58 Epstein 20G-138 2,897,327 7/59 Smidt et al 200-168 2,930,876 3/60 Siri 200-168 FOREIGN PATENTS 641,255 8/50 Great Britain.

BERNARD A. GILHEANY, Primary Examiner. MAX L. LEVY, Examiner, 

1. IN AN IMPROVED WALL THEREMOSTAT, THE IMPROVEMENT COMPRISING: A CIRCULAR MOUNTING PLATE HAVING A THIN DISC CONFIGURATION AND FORMED OF INSULATING MATERIAL AND DESIGNED FOR INDEPENDENT CONNECTION TO THE WALL, SAID PLATE BEING PROVIDED WITH A SET OF TERMINAL CONNECTIONS AND TERMINAL ARMS CONNECTED TO SAID TERMINAL CONNECTIONS, SAID MOUNTING PLATE UPON CONNECTION TO THE WALL HAVING SAID TERMINAL ARMS EXPOSED; A THERMOSTAT HOUSING REMOVABLY HELD TO THE MOUNTING PLATE AND HAVING ADJACENT SAID MOUNTING PLATE A HOLLOW REAR PORTION WITH A WALL POSSESSING AN INNER DIAMETER SLIGHTLY LARGER THAN THE DIAMETER OF SAID CIRCULAR MOUNTING PLATE PLACED ABOUT SAID MOUNTING PLATE; AND A SECOND SET OF TERMINAL ARMS SUPPORTED WITHIN SAID HOUSING WITH THEIR OUTER ENDS REMOVABLY INTERLOCKED WITH 